Pump plunger



Nov- 14, 1933- a. E. WENDLE r 1 PUMP PLUNGER Filed March 932 Patented Nov. 14, 1933 UNITED STATES PATENT OFFICE Claims.

This invention relates to improvements in pump plungers, and more especially to a novel plunger assembly for well pumps, and to special valve cups for use on the plunger.

Plunger pumps as found in the oil fields, consist essentially of an accurately ground working barrel which is generally stationary and fitted with a plunger precisely ground to a diameter from .003" to .006" less than the inside diameter 10 of the barrel. The plunger is reciprocated by suitable mechanical connections, and delivery of the oil or other fluid follows, but the pumping efficiency and delivery are dependent upon the maintenance of the small initial clearance which prevents any material slippage of the fluid past the plunger. Even under the best conditions, wear will take place on both the working barrel and metal plunger; this condition is usual and generally recognized. As a matter of fact, the

0 American Petroleum Institute has standard instructions for regrinding conventional types of plunger pumps, specifying that the first regrinding shall increase the diameter of working barrel .020", and the second regrinding increase the barrel diameter .040". In the same connection,

over-sized plungers are specified to fit the reground barrels.

These American Petroleum Institute standards are not as rigid as the practice of some of the large producing companies of regrinding in steps of .010" in order to maintain desired operating efliciency.

In addition to the normal wear on both barrel and plunger, there are regrinding jobs necessitated because sandor grit suspended in the fluid enters the small clearance space between plunger and barrel, and results in scoring either the barrel or plunger, or both.

These data will indicate the general experience in operating present types of plunger pumps, and those familiar with machining operations will appreciate the cost of frequent regrindings to accuracies of .001" to .002 in a barrel from 6 to 10 feet long, and of diameters from 1%" The primary purpose of the present invention is to eliminate the disadvantages present in the use of the conventional metal plungers, and also in the use of plungers having ordinary packing cups. In accordance with the invention, the rigid, cylindrical metal plunger is replaced by a central body or tube on which a series of composition valve cups of the proper outside diameter are mounted and adjusted to give a predetermined clearance in the working barrel, and are clamped securely on the plunger. The improved valve cups have certain elasticity to permit sand or grit to embed therein without scoring the barrel, and the ends of each cup are beveled and confined to prevent excessive expansion of the same. A definite small clearance between the plunger and barrel is provided by my [improved means for clamping the packing cups in position, and such means are designed to maintain a minimum clearance between the barrel and plunger.

With the foregoing objects outlined and with other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawing, and more particularly pointed out in the appended claims.

Inthe drawing,

Fig. 1 is an elevation of my improved plunger.

Fig. 2 is a vertical sectional view of the same, taken on the line 22 of Fig. 1.

Fig. 3 is a horizontal section on 33 Fig. 2.

Fig. 4 is an elevation of an improved cup washer.

Fig. 5 is a vertical sectional view of the same.

Referring to the drawing, 4 designates a valve cage of the plunger having a threaded shank 5 'at one'end designed to be attached to the rod string or the like of the pump. A conventional ball valve 6 in this cage rests on a seat 7 which is secured in position by a tube 8, that is screwed into the cage as shown at 9. Such tube has an enlarged polygonal portion 8 terminating at its lower end in an annular recess having a horizontal surface 10 and a bevel surface 10*, both engaged by the internal flange 11 at the base of one of the improved cup washers. Each of these washers is preferably formed of a suitable elastic composition, and comprises a tubular wall 11 having a cylindrical outer surface which merges at one end into a base flange 11 and is provided at its opposite end with a frusto-conical or beveled surface 12. It will be noted that the outer surface 13 of the flanged end of the cup is also of frusto-conical or tapered shape, for a purpose hereinafter explained. If the surfaces 12 and 13 are of frusto-conical shape, the angle of each is at about 40 to 50 relatively to the straight outer surface of the wall of the cup.

A spacing sleeve 14, preferably of cylindrical shape surrounds the cylindrical portion 1'5 of the tube and limits the inward movement of the cylindrical wall of the washer.

As shown in the drawing, a series of these washers is arranged on the tube 8, and between each two washers there is a combined spacing and confining ring 16, preferably formed of metal, and having its opposite faces recessed, as indicated at 17 to conform with the beveled or tapered ends of the cup washers. While each sleeve 14 is shown separate from the adjacent confining ring 16, it may be rigidly attached to or integral with such ring.

A nut 18 having an integral looped end 18 is threaded to the lower end of the tube, and functions to secure the members 11, 14 and 16 in assembled relation on the plunger.

Obviously, the composition cups 11 are nonrigid and penetrable as compared with the rigidity and impenetrability of a metal plunger and the spacing ring 14 of each cupmay be securely fastened to the cup.

Comparing the operating characteristics of the improved plunger with a standard plunger, it will be noted, first, with similar clearance, the efficiency and delivery will be the same for both plungers. Second, in my design, wear, due to friction, will take place more on the composition packing cups than on the metal wall of the barrel. With the standard metal plungers, wear takes place on both the plunger and barrel and will proceed until the resulting increased clearance requires regrinding of the barrel and purchase of a new over-sized metal plunger-a relatively expensive alteration. With my design, the wear on the barrel will be at a much slower rate, and the pumping efficiency and delivery can be brought back to normal at a low cost by refitting theplunger with new cups of proper outside diameter. Furthermore, as composition cups of my design are used, the plunger may efliciently operate in a barrel which may be slightly out of round, or that has slight surface inequalities. Owing to the relative softness of the wearing surface of my cups, particles of sand or grit which would probably score the metal barrel and plunger, embed in these softer cups and thereby avoid scoring or damaging of the wall of the barrel. Third, the metal plunger is, for practical reasons, limited in its application to accurately ground working barrels, and is not adapted for use in the common cold drawn steel barrels in which the tolerance limits accepted are much larger-plus or minus .008". The adjustments of the packing cup diameter readily made with my improved plunger, will permit its use efficiently in these cold drawn barrels which are in more extensive use than the accurately ground barrels. Hitherto, cold drawn barrels were operated with plungers equipped throughout with the. conventional types of packing cups which were clamped at the base and free at the top to expand outwards under the fluid pressure. Due to over stressing of conventional cups in the deeper wells, frequent renewals of the cups were required, with the attendant expense of pulling the well. Knowing the inside diameter of the cold drawn barrel, my improved plunger can be fitted with my special cups of the proper diameter to give correct operating clearance in the barrel, and thereby renewal costs are materially reduced. This will be evident when it is observed that my special cups are clamped at both ends, while the usual cups are only clamped at the base.

If well conditions, sand, etc., require some wiplng action of the walls of the barrel, then a modification can be made by using the special clamped cups at the top and bottom of the plunger, and

by omitting the top clamps (formed by the rings 16) from the intermediate cups. In such a construction, the tops of the intermediate cups will expand to the barrel and will wipe the wall clean at each stroke. At the same time, the special clamped nuts at the ends of the plunger will take the greater part of the heavy fluid pressureand protect these intermediate cups against the full fluid pressure. Obviously, this protection will materially increase the service life of the intermediate cups. In addition, the presence of the intermediate cups will insure maintained pumping efliciency and delivery after the wear of the top clamped cup has resulted in too great clearance.

The net operating result of this action is that the full working life of the clamped top and bot tom cups is supplemented by the working life of the intermediate cups, and greater service life obtained from the improved plunger assembly.

Reverting to the specially shaped cups which I employ, it will be noted that all makes of valve cups have a straight section of side wall extending from the top edge to the heel curve which starts approximately circular but gradually increases in radius until practically flat at the edge of the hole in the base. Such side wall extends beyond and above the supporting surface, is straight at the top and curved some distance from its base support. In other words, such side wall forms a defective column structure and is badly distorted when subjected to the fluid pressure in wells of even modern depth. Furthermore, the effect of the vertical fluid pressure results in jamming the entire side wall downward and damaging its structure; and there is added damage due to the outward movement of the cup under the horizontal pressure. The form of the side wall and base of a conventional cup, together with the lack of any effective resistance by the cup ring seat, demonstrates clearly the weakness of the cups heretofore known.

In accordance with my invention, it will be observed that the base or flanged end of each cup conforms to the shape of the seat at the base of the cup, as indicated at 1'7, and consequently, the wall cannot be distorted to any appreciable degree against such seat, and as the mouth of the .of each cup, and prevents the damaging distortion inherent in the cups heretofore proposed.

From the foregoing it is believed that the constructions, operation and advantages of my invention may be readily understood by those skilled in the art, and it is apparent that changes may be made in the details disclosed, without departing from the spirit of the invention, as expressed in the claims.

What I claim and desire to secure by Letters Patent is:

1. A plunger including a packing cup comprising an annular wall of a yielding composition having substantially frusto-conical surfaces at each end thereof converging toward the extremities of the cup and provided at its base end with an inwardly extending annular flange having an outer surface merging into the substantially frusto-conical surface at that end of the cup, and a spacing ring of about the same height as said wall, arranged on the plunger and within the cup, the external diameter of the ring being substalriltially equal to the internal diameter of said we 2. A pump plunger comprising a body surrounded by spaced packing cups of a yielding composition, certain of said cups being provided at their ends with substantially conical outer surfaces, confining surfaces arranged on the plunger and having portions complementary to certain of said substantially frusto-conical surlfaces and engaging the latter, and spacing rings arranged on the plunger and positioned within the cups, each ring being of about the same height as the wall of the cup with which it is associated and having an external diameter substantially equal to the internal diameter of said wall. a

3. A pump plunger comprising a body surrounded by spaced packing cups of a yielding composition, certain of said cups having annular walls and being provided at their ends with substantially conical outer surfaces, confining surfaces arranged on the plunger and having portions complementary to certain of said substantially frusto-conical surfaces and engaging the latter for restricting the openings of the mouths of the cups, and spacing rings arranged on the plunger and within the cups, each ring being of about the same height as the wall of the cup with which it is associated and having an external diameter substantially equal to the internal diameter of said wall.

4. A pump plunger comprising a body surrounded by spaced packing cups of a yielding composition, certain of said cups being provided at their ends with substantially conical outer surfaces, confining surfaces arranged on the plunger and having portions complementary to certain of said substantially frusto-conical surfaces and engaging the latter, and spacing rings arranged on the plunger and positioned within the cups.

5. A pump plunger comprising a tubular body, a series of packing cups of a yielding composition surrounding said body, spacing rings arranged on the body between said cups, each spacing ring having cavities in its opposite faces, adjacent cup washers extending into said cavities, and having surfaces conforming to the surfaces of the cavities.

6. A pump plunger comprising a tubular body, a series of packing cups of a yielding composition surrounding said body, spacing rings arranged on the body between said cups, each spacing ring having cavities in its opposite faces, adjacent cup washers extending into said cavities and having surfaces conforming to the surfaces of the cavities, adjacent spacing rings receiving opposite ends of a packing cup and clamping the latter to the body.

7. A pump plunger comprising a tubular body, a series of packing cups of a yielding composition surrounding said body, spacing rings arranged on the body between said cups, each spacing ring having cavities in its opposite faces, adjacent cup washers extending into said cavities and having surfaces conforming to the surfaces of the cavities, adjacent spacing rings receiving opposite ends of a packing cup and clamping the latter to the body, and spacing sleeves positioned within the cup washers and clamping the bases of the latter on said body.

8. A pump plunger provided with a tubular portion, a series of cup washers of yielding composition surrounding said body, spacing sleeves in the washers bearing against the bases of the washers, spacing rings snugly engaging said body and arranged between adjacent cup washers, said rings being of less diameter than said washers and provided with cavities into which opposite ends of certain of the washers extend.

9. A pump plunger provided with a tubular portion, :a series of cup washers of yielding composition surrounding said body, spacing sleeves in the washers bearing against the bases of the washers, spacing rings snugly engaging said body and arranged between adjacent cup washers, said rings being of less diameter than said washers and provided with cavities into which opposite ends of certain of thewashers extend, the portions of the washers which extend into the cavities conforming 'to the shape of said cavities.

10. A pump plunger provided with a tubular portion, a series of cup washers of yielding composition surrounding said body, spacing sleeves in the washers bearing against the bases of the washers, spacing rings snugly engaging said body and arranged between adjacent cup washers, said rings being of less diameter than said washers and provided with cavities into which opposite ends of certain of the washers extend, and a nut having threaded engagement with the plunger tube and securing said washers, sleeves and rings on the tube.

GEORGE E. WENDLE. 

